Interactional Aerodynamic Insight Obtained from Wind Tunnel Testing and Computational Analysis

Interactional aerodynamic interactions between various rotorcraft components can make a large contribution to steady and unsteady loads, performance, and vibration. Wind tunnel results from a powered model test have been analyzed to identify trends in the unsteady aerodynamic pressures on the horizontal stabilizer. Flow velocity measurements were also made behind the fuselage, rotor hub, and blades. Velocity components in all three directions were separated into time-averaged, periodic, and broadband components to identify factors contributing to unsteady tail loads and provide validation data for analysis. Computational Fluid Dynamics (CFD) has been applied to four configurations of the wind tunnel model. The calculated steady rotor and fuselage forces and the unsteady tail pressures have been compared to experiment. CFD has also been applied to a flight test configuration and the results compared to measured stabilizer accelerations. When all relevant components are included, the CFD analysis captures many key features, but there remains room for improvement in resolving the quantitative details.